Polymeric colorants are widely used in thermoplastics and thermosetting polymers, such as polyurethanes. Polymeric colorants that are non-staining to skin and fabric have found utility in coloring personal and home care products, art products, coatings and inks, and the like. In general, polymeric colorants comprise chromophore moieties and polymeric chains. If the polymeric chains are very long comparing to the chromophores, then the color strength of the polymeric colorants is generally weak. The application for use of these colorants is thus somewhat limited. If the polymeric chains are short, the materials tend to be a paste or viscous liquid. Most of the high color strength polymeric colorants are either sticky liquids or viscous pastes in their undiluted state. These polymeric colorants generally need to be diluted with water or organic solvents to allow convenient handling before being used to color various products. This additional level of solvent may create challenges in the physical properties for certain end-use applications. Furthermore, these liquid formulations of polymeric colorants are often difficult to handle during some manufacturing and application processes, particularly when the final product is a hard solid or powder. Thus, the need exists for a free-flowing solid form of polymeric colorants which allows the polymeric colorant to be utilized in new applications or to be used more easily in existing applications.
There are several ways to make solid polymeric colorants, as disclosed in patents and literature. U.S. Pat. No. 5,411,802 to Kumar et al. discloses a process to make solid color particles by polymerization of formaldehyde, urea, polyamine, and a dye. The colored particles have a size of between 1 and 70 microns and are easily washable when incorporated into a washable formulation.
U.S. Pat. No. 3,945,980 to Tsubakimoto et al. describes finely divided colored or uncolored hardened resin particles made by benzguanamine, melamine, formaldehyde, curing catalyst and others. The colored particles are not soluble in water or other solvents, and they cannot be released to color other articles.
U.S. Pat. No. 4,167,422 to Bellanca et al. discloses organic color pigment lakes comprised of a high molecular weight polymeric dye adsorbed on water insoluble substrates such as alumina. The formed polymeric color lakes are non-bleeding when used in food systems and other industrial applications. When colorants are covalently incorporated into particles, the colorants are no longer water soluble. Thus, there are limitations on the type of chromophore that can be utilized and on how much the colors can be reacted into the particle.
The present disclosure provides methods and processes for converting these liquid and/or paste polymeric colorants into free-flowing powders having relatively high color strength. These free-flowing polymeric colorants are useful for coloring any material that benefits from having a non-permanent, washable colorant contained therein. Exemplary end-use materials include solid pucks, tablets, powder detergents, soaps, liquid detergents, fabric softeners, cleaning compositions, coatings, inks, personal care products, plastics and candles.